PC: Huge thanks for the heads up! I was suspicious because of the low number of votes for posts newer than 31 March. Turns out, only me and regular commenters could see the new posts. The problem was with the site cache (NOT related to your browser cache), which is turned off by default for commenters (so that they can see their own comments, comments preview, etc.) and for admin (for obvious reasons).

Sometimes only user feedback can save the situation, because I don’t see the site the same way as most of the visitors.